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Flicker emission, voltage fluctuations, and mechanical loads for small-scale stall- and yaw-controlled wind turbines

Mohammadi, Ebrahim, Fadaeinedjad, Roohollah, Naji, Hamid Reza
Energy conversion and management 2018 v.165 pp. 567-577
algorithms, blades, electric power, mechanical loads, wind speed, wind turbines
This study analyzes and compares flicker emission, voltage fluctuations, and mechanical loads for two small-scale wind turbines (WTs), considering different control strategies. The investigated strategies are active yaw and stall control strategies for above rated wind speed operation to limit the captured power. The yaw controller is designed to limit the output power and rotation speed in high wind speeds by rotating the turbine out of the wind direction. On the other hand, the optimal blades are designed for the stall-controlled WT to have appropriate performance in all wind speed regions, especially in the stall region. In this WT, the captured power is regulated by controlling the rotor speed in relation to wind speed via power electronic interface in all wind speed regions without requiring the aerodynamic active devices. The maximum power point tracking (MPPT) algorithms are also implemented in low and moderate wind speeds. A simulation platform is used that considers aerodynamic, mechanical, electrical, and control aspects of the WTs. The MPPT, yaw and stall control, and simulation results are presented and discussed. Results demonstrate that flicker emission level, voltage fluctuation and mechanical loads for the stall-controlled WT are less than those in the yaw-controlled turbine.